Forgot to make output
First, despite the fact that it appears to be out of scope for the site, I'm answering this question because the question and your reputation on the site suggest to me that you are a beginning Blenderhead. Although it seems to me that your question is more about the operating system on your device, than about the internals of Blender, a beginner might not easily recognize where Blender ends, and the operating system begins. I would suggest you take the tour, and review the sections of the help center related to asking questions. 

That written, the information in the question is a bit sparse. It would be helpful to know, for example, what OS (Mac, Linux, Windows) you are using. What I would try first in Windows is to open the a file folder window, and select the "Computer" option in the navigation pane on the left. In the search box in the upper right hand corner of the window, search for any file modified beginning with a time several hours before you started the render. For example, suppose you know you started the render within the past 12 hours, search for all files modified today. If the render got saved (and I'm not at all sure that it was) this search parameter should produce results for all such files the search finds on your computer, including any drives assigned a drive letter. The file you rendered to should be found in that list. The time modified should be about the same time as you started the render.

If you don't find the file you rendered to in the list, it's possible that you failed to specify a location to which to save, and that you need to render the scene again.